IOWA CITY, Iowa — Investigators confirmed Friday they are looking into an unusual claim of jury tampering in a medical-malpractice trial in which University of Iowa Hospitals and Clinics recently avoided millions in damages.After a three-week trial, a Johnson County jury ruled Feb. 23 that the hospital was negligent in caring for a mother who suffered complications before giving birth in 2010. But jurors found that negligence was not a cause of damage to the girl — who suffered brain damage and is severely …